change RegexTerm _internalname to "regexp" to match ES DSL
Merge pull request #457 from toconnor/master

change RegexTerm _internal_name to "regexp" to match ES DSL
Allow query_weight and rescore_query_weight to be zero.
Merge pull request #460 from maciejkula/bug/rescore_weights_zero

Allow query_weight and rescore_query_weight to be zero.
Merge branch 'master' of https://github.com/aparo/pyes into feature/es_official_client